The invention relates to a blood treatment device, in particular a dialysis machine, which has a blood treatment unit, in particular a dialyzer. The invention further relates to a disposable kit for such a blood treatment device.
Various dialysis methods are known. In dual-needle dialysis, blood is drawn off from a patient via one needle and returned to the patient via another needle. In this case, the blood is pumped continuously through the dialyzer. Single-needle dialysis requires only one needle in order to draw off and return blood cyclically, as the arterial and venous blood lines are connected to the same needle.
Single-needle and dual-needle dialysis machines generally make use of occluding tube pumps. Dialysis machines are known, however, in which positive displacement pumps are used to pump the blood.
DE 39 11 587 A1 describes a single-needle dialysis machine, in which the blood, in a first phase, is drawn off by a needle via an arterial branch and, in a second phase, is returned via a venous branch by the same needle. In order to make it possible to achieve continuous blood flow via the dialyzer, even in the case of single-needle dialysis, compensation chambers are connected into the arterial and venous branches. Single-needle dialysis is less stressful for the patient, but the control of the blood flow via the common needle is more demanding than in the case of dual-needle dialysis.
WO84/02473 and WO98/22165 disclose blood treatment devices in which various components that form a functional unit are combined in a cassette. This modular design has the advantage that the parts of the system coming into contact with the blood can be replaced easily. A disadvantage, however, is that the flow plan is dictated by the design of the model. If, for example, the module is to be configured for dual-needle operation, then single-needle operation is not possible, or vice versa.
It is an object of the invention to offer a blood treatment device which allows both single-needle and dual-needle operation, without great changes having to be made to the flow plan of the device. It is another object of the invention to provide a disposable kit for such a blood treatment device.
These objects are achieved according to the invention by providing, for example, a blood treatment device that includes a blood treatment unit having an inlet and an outlet. A feed line is connected to the inlet of the blood treatment unit, the feed line has a first branch line and a second branch line. Also provided is a return line connected to the outlet of the blood treatment unit. Included is a first positive displacement pump connected in the first line branch, the first pump divides the line branch into a first section and a second section. A first closure member is provided in the first section of the first line branch, and a second closure member is provided in the second section of the first line branch. Additionally, a second positive displacement pump is connected in the second line branch, the second pump divides the second line branch into a first section and a second section. A third closure member is provided in the first section of the second line branch, a fourth closure provided in the second section of the second line branch. A connection line, having a fifth closure member, connects the outlet of the blood treatment unit to the first line branch or the second line branch.
The term blood treatment device is intended to mean all devices that have an extracorporeal circuit with a unit for treating blood. These include, in particular, devices for hemodialysis, hemofiltration and hemodiafiltration but also, for example, cell separators.
For the delivery of blood, the blood treatment device has two positive displacement pumps, preferably diaphragm pumps, with the first pump being connected into the first line branch and the second pump being connected into the second line branch of a branching feed line, through which the blood is drawn off from the patient and supplied to the blood treatment unit, for example the dialyzer. The blood from the blood treatment unit is returned via a discharge line.
For dual-needle operation, a needle is attached both to the feed line and the return line. The two pumps operate alternatively. While one pump is taking blood in, the other pump delivers blood into the blood treatment unit, so that blood flows continuously through the blood treatment unit.
A connection line for producing a fluid connection between the outlet of the blood treatment unit and one of the two pumps permits single-needle operation without great changes to the flow plan. The feed and return lines are connected to a common needle during single-needle operation. In a first phase, both pumps take blood in via the open fluid connection, with the blood flowing through the first pump and the blood treatment unit to the second pump. The blood is not returned via the return line in this phase. In a subsequent second phase, the fluid connection remains open, with both pumps delivering blood that is returned via the return line.
In an alternative embodiment, the common needle may be attached only to the feed line, with the blood being drawn off and returned only via the feed line in this embodiment.
The parts of the blood treatment device that come into contact with the blood are preferably designed as a disposable kit, although they may also be part of the blood treatment device.
The disposable kit for the blood treatment device has a feed line with two parallel line branches, and a return line, and pump chambers connected into the first and second line branches, as well as a connection line. The disposable kit may, however, also comprise yet other components, for example main chambers etc. The blood treatment unit may also be part of the disposable kit.
The disposable kit may be designed as a tube set. It is, however, also possible to fit all parts of the disposable kit in one functional unit, for example in the form of a film part.
The blood treatment unit preferably has a holding unit, known from the prior art, into which the disposable kit is put. The pumps and closure members for controlling the blood flow are then part both of the disposable kit and of the holding unit. Disposable kits and holding units having such pumps and closure members are, for example, described in DE 198 14 695 A1, and WO 99/17019, the disclosure of which is herein incorporated by reference.
The advantages of the invention are most pronounced when the parts coming into contact with the blood are designed as a disposable kit, which is put into the holding unit on the machine side. To perform single-needle operation, only minor changes need to be made to the disposable kit and to the holding unit. To that end, only a short sealable tap line is required, which should be as short as possible so that the dead volume is small.